The Delta variant of SARS-CoV-2, first identified in India, has mutated to form Delta plus or AY.1 variant. Delhi's CSIR-IGIB scientist Vinod Scaria on Sunday tweeted, "One of the emerging variants is B.1.617.2.1 also known as AY.1 characterised by the acquisition of K417N mutation." However, there is no cause for concern as of now, CSIR-IGIB Director Dr Anurag Agrawal said.